PHP aes （ecb）解密后乱码问题

function apiDataDecrypt($data, $key='') {  $data = base64_decode($data);  $pad = 16 - (strlen($data) % 16);  $padData = $data . str_repeat(chr($pad), $pad);  return mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,$padData, MCRYPT_MODE_ECB);}    }

$key = '1234567890123456';$content = 'T7UT2NQ1AFvR9unjA0wKWA==';$desStr = decryptString($content,$key);echo($desStr);function decryptString($str,$key) {  $str = base64_decode($str);  $str = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key, $str, MCRYPT_MODE_ECB);    $block = mcrypt_get_block_size('rijndael_128', 'ecb');  $pad = ord($str[($len = strlen($str)) - 1]);  $len = strlen($str);  $pad = ord($str[$len-1]);    return substr($str, 0, strlen($str) - $pad);}